in just two hours. Opaque plastic cartons reduce the flow of light into the milk but do not
block it completely.
Preparing This Food
Chill, pour, and serve. Never pour unused milk or cream back into the original container. Doing
that might introduce bacteria that can contaminate all the other milk in the bottle or carton.
What Happens When You Cook This Food
When milk is warmed, its tightly-curled protein molecules relax and unfold, breaking inter-
nal bonds (bonds between atoms on the same molecule) and forming new, intermolecular
bonds between atoms on neighboring molecules. The newly linked protein molecules create
a network with water molecules caught in the net. As the milk cooks, the network tightens,
squeezing out the water molecules and forming the lumps we call curds.
Casein, the proteins that combine with calcium to form the “skin” on top of hot milk,
will also form curds if you make the milk more acid by adding lemon juice, fruit, vegetables,
vinegar, or wine. Whey proteins do not coagulate when you make the milk more acid, but
they precipitate (fall to the bottom of the pot) when the milk is heated to a temperature
above 170°F. If the bottom of the pot gets hotter, the whey proteins will scorch and the milk
will smell burnt.
How Other Kinds of Processing Affect This Food
Freezing. Milk that has been frozen and defrosted has less vitamin C and B vitamins than
fresh milk. Freezing also changes the taste and texture of milk. First, it breaks up milk’s pro-
tein molecules. When the milk is defrosted, they clump together so that the milk no longer
tastes perfectly smooth. Second, freezing slows but does not stop the natural oxidation of
milk’s fat molecules. The longer milk is frozen, the more fat molecules will oxidize and the
stronger the milk will taste.
Drying. Dried milk tastes cooked because it has been heated to evaporate its moisture.
Unopened packages of dried milk should be stored in a cool, dry cabinet where they may hold
their flavor and nutrients for several months. Once dried milk is opened, it should be stored in
a tightly closed container to keep out the moisture that will encourage bacterial growth and
change the flavor of the milk. Once the dried milk is reconstituted, it should be refrigerated.
Condensed and evaporated milk. Evaporated and condensed milks have been cooked to
evaporate moisture; condensed milk has added sugar. Both evaporated and condensed milk
have a cooked flavor. They also have less vitamin C and vitamin B 6 than fresh milk.
Unopened cans of condensed or evaporated milk should be stored in a cool, dark cabi-
net. Unopened cans of evaporated milk will keep for one month at 90°F, one to two years at
70°F, and two years or more at 39°F. At the same temperatures, unopened cans of condensed
Milk, Fresh